Table Of Contents<\/h3>\n\n- 1. Why do we need Docker?<\/a><\/dt>\n
- 2. Machines, Images and Containers<\/a><\/dt>\n
- \n
\n- 2.1. Installing docker and docker-machine<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 3. Understanding the commands<\/a><\/dt>\n
- \n
\n- 3.1 Creating a machine<\/a><\/dt>\n<\/dl>\n
\n- 3.2 Creating an image<\/a><\/dt>\n<\/dl>\n
\n- 3.3 Creating a container<\/a><\/dt>\n<\/dl>\n
\n- 3.4 Cleaning the environment<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 4.Running integration tests with Maven<\/a><\/dt>\n
- \n
\n- 4.1 Maven configuration<\/a><\/dt>\n<\/dl>\n
\n- 4.2 Creating the tests<\/a><\/dt>\n<\/dl>\n
\n- 4.3 Running the tests<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 5.Download the source code<\/a><\/dt>\n<\/dl>\n<\/div>\n
<\/a>1. Why do we need Docker?<\/h2>\n![\"docker\"](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2016\/05\/dockerlogo-300x295.jpg\")
<\/a>Docker is a tool to avoid the usual headaches of conflicts, dependencies and inconsistent environments, which is an important problem for distributed applications, where we need to install or upgrade several nodes with the same configuration.<\/p>\nDocker is a container manager, which means that is able to create and execute containers that represent specific runtime environments for your software. In contrast with virtual machines like VirtualBox, Docker uses resource isolation features of the Linux kernel to allow independent \u201ccontainers\u201d to run within a single Linux instance, avoiding the overhead of starting and maintaining virtual machines. A computer with docker can run multiple containers at the same time.<\/p>\n
Therefore, the automation of Docker mainly offers facilities for integration tests and continuous delivery.<\/p>\n
<\/a>2. Machines, Images and Containers<\/h2>\nIn order to use docker, it is important to have clear some vocabulary. Docker distinguishes three important concepts: docker machines, docker images and containers.<\/p>\n
Docker containers are executions of an specific runtime environment. For example, to simulate a machine with an specific database up. These runtime environments are called Docker images, which are the result of executing the set of commands that appear in an specific script-like file called Dockerfile<\/code>. Therefore, Docker allow having multiple containers of an specific Docker image. These could be compared with the concepts of program and process. Indeed, containers like processes, can be created, stopped, died, or running.<\/p>\nDocker machines are local (and virtual) machines or remote machines(e.g in a cloud such as Amazon AWS or DigitalOcean) with a docker running. Like physical machines, docker machines has an specific IP address. Each docker machine can manage multiple docker images and containers. From our own personal computer, the docker-machine command, allow us connecting to all our docker machines to manage their containers and images.<\/p>\n
![\"docker](\"http:\/\/examples.javacodegeeks.com\/wp-content\/uploads\/2016\/05\/docker-mchine-me.jpg\")
<\/a><\/p>\n<\/a>2.1. Installing docker and docker-machine<\/h3>\nFollow the next steps to install docker and docker machine<\/p>\n
\n- Download and install the docker binary file from here<\/a>.Once, you have followed the installation instructions, you should be able to run the following command.
\nDocker installation test<\/em><\/span><\/p>\n$ docker run ubuntu:14.04 \/bin\/echo 'It works!'\nIt works!\n<\/pre>\n<\/li>\n
- Download the Docker Machine binary and update your
PATH<\/code>.If you are running OS X or Linux:
\nUnix Docker Machine installation<\/em><\/span><\/p>\n$ curl -L https:\/\/github.com\/docker\/machine\/releases\/download\/v0.6.0\/docker-machine-`uname -s`-`uname -m` > \/usr\/local\/bin\/docker-machine && \\\nchmod +x \/usr\/local\/bin\/docker-machine\n<\/pre>\nIf you are running Windows with git bash
\nWindows Docker Machine installation<\/em><\/span><\/p>\n$ if [[ ! -d \"$HOME\/bin\" ]]; then mkdir -p \"$HOME\/bin\"; fi && \\\ncurl -L https:\/\/github.com\/docker\/machine\/releases\/download\/v0.6.0\/docker-machine-Windows-x86_64.exe > \"$HOME\/bin\/docker-machine.exe\" && \\\nchmod +x \"$HOME\/bin\/docker-machine.exe\"\n<\/pre>\nOtherwise, simply use the installer from the Docker official releases<\/a>.<\/li>\n<\/ul>\n<\/a>3. Understanding the commands<\/h2>\nThere are many docker commands. In fact, if we run simply docker<\/code> from our terminal, we can see all the available commands.<\/p>\nDocker commands<\/em><\/span><\/p>\nCommands:\n attach Attach to a running container\n build Build an image from a Dockerfile\n commit Create a new image from a container's changes\n cp Copy files\/folders from a container to a HOSTDIR or to STDOUT\n create Create a new container\n diff Inspect changes on a container's filesystem\n events Get real time events from the server\n exec Run a command in a running container\n export Export a container's filesystem as a tar archive\n history Show the history of an image\n images List images\n import Import the contents from a tarball to create a filesystem image\n info Display system-wide information\n inspect Return low-level information on a container or image\n kill Kill a running container\n load Load an image from a tar archive or STDIN\n login Register or log in to a Docker registry\n logout Log out from a Docker registry\n logs Fetch the logs of a container\n pause Pause all processes within a container\n port List port mappings or a specific mapping for the CONTAINER\n ps List containers\n pull Pull an image or a repository from a registry\n push Push an image or a repository to a registry\n rename Rename a container\n restart Restart a running container\n rm Remove one or more containers\n rmi Remove one or more images\n run Run a command in a new container\n save Save an image(s) to a tar archive\n search Search the Docker Hub for images\n start Start one or more stopped containers\n stats Display a live stream of container(s) resource usage statistics\n stop Stop a running container\n tag Tag an image into a repository\n top Display the running processes of a container\n unpause Unpause all processes within a container\n version Show the Docker version information\n wait Block until a container stops, then print its exit code\n\nRun 'docker COMMAND --help' for more information on a command.\n<\/pre>\nIn this section, we will see how to manage docker machines, how to pull a docker image using an specific docker machine and how to create a container for such docker image.
<\/div> <\/div><\/p>\n<\/a>3.1 Creating a machine<\/h3>\nFirst of all, we will list the set of available docker machines with the following command:<\/p>\n
List Docker Machines<\/em><\/span><\/p>\ndocker-machine ls\n<\/pre>\nIn case of not having any machine, we are going to create a new one as follows:<\/p>\n
Docker installation test<\/em><\/span><\/p>\ndocker-machine create --driver virtualbox default\n<\/pre>\nNotice that in order to create a docker machine, we need to specify a driver, which will determine if it is a virtual machine, in this case virtual box, or if it is a connection to docker running in an external machine.<\/p>\n
<\/a>3.2 Creating an image<\/h3>\nDocker images are created in an specific docker machine. In order to define the docker machine that we want to use, we need to run the following command:<\/p>\n
Select docker machine<\/em><\/span><\/p>\neval \"$(docker-machine env default)\"\n<\/pre>\nIn order to check the effects, list the available docker machines again. At this moment, a new machine should appear with a new IP address (192.168.99.100) and contains an asterisk in the ACTIVE<\/code> column.<\/p>\nActive Docker Machine<\/em><\/span><\/p>\nNAME ACTIVE DRIVER STATE URL SWARM\ndefault * virtualbox Running tcp:\/\/192.168.99.100:2376 \n<\/pre>\nDocker images are the binary files of runtime environments. The contents of a docker image are the result of executing the set of instructions that appear in a plain text file called Dockerfile<\/code>. However, in order to avoid building docker images from Dockerfiles over and over again, there is an online repository for docker images called Docker Hub<\/a>.<\/p>\nFor example, in order to pull a MongoDB image, we only need to execute the docker pull command as follows:<\/p>\n
Docker pull command<\/em><\/span><\/p>\ndocker pull mongo\n<\/pre>\nIn order to see the installed docker images in our docker machine, use the following command. Notice that a new entry appears with the Mongo image. Each image has a unique identifier of the docker image for our machine called IMAGE ID<\/code>.<\/p>\nList Docker Images<\/em><\/span><\/p>\ndocker images\n<\/pre>\nIf you are interested to understand how to create a Dockerfile<\/code>, we strongly recommend follow this<\/a> example.<\/p>\n<\/a>3.3 Creating a container<\/h3>\nDocker containers are executions of docker images. In order to create a container from an image, we use the command docker run. For example:<\/p>\n
List Docker Images<\/em><\/span><\/p>\ndocker run mongo\n<\/pre>\nAfter that, we can check the list of containers, with the following instruction.<\/p>\n
List docker containers<\/em><\/span><\/p>\ndocker ps -a\n<\/pre>\nNotice that our container has an identifier too, called CONTAINER ID<\/code>. We will use it later.<\/p>\nThe IP address to connect to this container from our application is the IP of our docker machine (192.168.99.100).<\/p>\n
<\/a>3.4 Cleaning the environment<\/h3>\nAt this point we have downloaded a docker machine and we have started a docker container. In order to stop and remove the container and the image we need to execute the following instructions:<\/p>\n
Stop the container:<\/p>\n
Stop Docker Container<\/em><\/span><\/p>\ndocker stop #containerId\n<\/pre>\nRemove the container:<\/p>\n
Remove Docker Container<\/em><\/span><\/p>\ndocker rm #containerId\n<\/pre>\nRemove the docker image:<\/p>\n
Remove Docker Image<\/em><\/span><\/p>\ndocker rmi #imageId\n<\/pre>\n<\/a>4.Running integration tests with Maven<\/h2>\nThere are different approaches to design integration tests with Docker. In this example, we will design a Maven project, which before executing JUnit tests, it automatically starts a MongoDB Docker container.<\/p>\n
<\/a>4.1 Maven configuration<\/h3>\nFirst of all, copy this pom.xml<\/code> file. We are going to use the docker-maven-plugin<\/code> to automatically load the defined Docker images and create a container before running the integration tests. In order to support integration tests, we use the maven-failsafe-plugin<\/code>.<\/p>\npom.xml<\/em><\/span><\/p>\n<project xmlns=\"http:\/\/maven.apache.org\/POM\/4.0.0\" xmlns:xsi=\"http:\/\/www.w3.org\/2001\/XMLSchema-instance\"\n\txsi:schemaLocation=\"http:\/\/maven.apache.org\/POM\/4.0.0 http:\/\/maven.apache.org\/xsd\/maven-4.0.0.xsd\">\n\t<modelVersion>4.0.0<\/modelVersion>\n\n <groupId>javacodegeeks<\/groupId>\n\t<artifactId>javacodegeeks<\/artifactId>\n\t<version>1.0-SNAPSHOT<\/version>\n\t<packaging>jar<\/packaging>\n\n\n <properties>\n <project.build.sourceEncoding>UTF-8<\/project.build.sourceEncoding>\n <project.build.resourceEncoding>UTF-8<\/project.build.resourceEncoding>\n <maven.compile.encoding>UTF-8<\/maven.compile.encoding>\n <\/properties>\n\n <build>\n <plugins>\n \n <plugin>\n <artifactId>maven-compiler-plugin<\/artifactId>\n <version>2.1<\/version>\n <configuration>\n <source>1.8<\/source>\n <target>1.8<\/target>\n <encoding>UTF-8<\/encoding>\n <\/configuration>\n <\/plugin>\n <plugin>\n <groupId>org.apache.maven.plugins<\/groupId>\n <artifactId>maven-failsafe-plugin<\/artifactId>\n <version>2.19.1<\/version>\n <configuration>\n <includes>\n <include>**\/IntegrationTest.java<\/include>\n <\/includes>\n <\/configuration>\n <executions>\n <execution>\n <id>integration-test<\/id>\n <goals>\n <goal>integration-test<\/goal>\n <\/goals>\n <\/execution>\n <execution>\n <id>verify<\/id>\n <goals>\n <goal>verify<\/goal>\n <\/goals>\n <\/execution>\n <\/executions>\n <\/plugin>\n <!-- Tell surefire to skip test, we are using the failsafe plugin -->\n <plugin>\n <groupId>org.apache.maven.plugins<\/groupId>\n <artifactId>maven-surefire-plugin<\/artifactId>\n <version>2.10<\/version>\n <configuration>\n <skip>true<\/skip>\n <\/configuration>\n <\/plugin>\n <plugin>\n <groupId>io.fabric8<\/groupId>\n <artifactId>docker-maven-plugin<\/artifactId>\n <version>0.15.0<\/version>\n <configuration>\n <logDate>default<\/logDate>\n <autoPull>true<\/autoPull>\n <dockerHost>tcp:\/\/192.168.99.100:2376<\/dockerHost>\n <certPath>${user.home}\/.docker\/machine\/certs\/<\/certPath>\n <images>\n <image>\n <name>mongo<\/name>\n <run>\n <ports>\n <port>27017:27017<\/port>\n <\/ports> \n <\/run>\n <\/image>\n \n <\/images>\n <\/configuration>\n <!-- Hooking into the lifecycle -->\n <executions>\n <execution>\n <id>start<\/id>\n <phase>pre-integration-test<\/phase>\n <goals>\n <goal>start<\/goal>\n <\/goals>\n <\/execution>\n <execution>\n <id>stop<\/id>\n <phase>post-integration-test<\/phase>\n <goals>\n <goal>stop<\/goal>\n <\/goals>\n <\/execution>\n <\/executions>\n <\/plugin>\n <\/plugins>\n <\/build>\n <dependencies>\n <dependency>\n\t <groupId>org.mongodb<\/groupId>\n\t <artifactId>mongo-java-driver<\/artifactId>\n\t <version>3.2.2<\/version>\n <\/dependency>\n <dependency>\n <groupId>junit<\/groupId>\n <artifactId>junit<\/artifactId>\n <version>4.12<\/version>\n <scope>test<\/scope>\n <\/dependency>\n <\/dependencies>\n <\/project>\n<\/pre>\n<\/a>4.2 Creating integration tests<\/h3>\nIntegration tests are executed after creating a MongoDB container by the maven-docker-plugin<\/code>. We are going to create a test to validate the following Zoo<\/code> component, which only has one operation called addAnimal<\/code> that inserts an animal to MongoDB.[ulp id=’6PVIvOz3kDbYmNRn’]<\/p>\nZoo.java<\/em><\/span><\/p>\npackage javacodegeeks;\n\nimport org.bson.Document;\n\nimport com.mongodb.MongoClient;\n\npublic class Zoo {\n\n\tprivate MongoClient client;\n\n\tpublic Zoo(MongoClient client) {\n\t\tthis.client = client;\n\t}\n\n\tpublic void addAnimal(String name, String type) {\n\t\tDocument doc = new Document(\"name\", \"lion\").append(\"type\", \"mammal\");\n\t\tclient.getDatabase(\"mydb\").getCollection(\"animals\").insertOne(doc);\n\t}\n}\n<\/pre>\nTo test the Zoo<\/code> component, we just validate, with an empty database, that after invoking the addAnimal<\/code> operation, MongoDB contains a new animal.<\/p>\nIntegrationTest.java<\/em><\/span><\/p>\npackage javacodegeeks;\n\nimport org.bson.Document;\nimport org.junit.AfterClass;\nimport org.junit.Assert;\nimport org.junit.BeforeClass;\nimport org.junit.Test;\nimport com.mongodb.MongoClient;\nimport com.mongodb.client.FindIterable;\nimport com.mongodb.client.MongoDatabase;\n\npublic class IntegrationTest {\n\n\tprivate static MongoClient client;\n\n\t@BeforeClass\n\tpublic static void start() {\n\t\tclient = new MongoClient(\"192.168.99.100\");\n\t\tMongoDatabase db = client.getDatabase(\"mydb\");\n\t\tdb.createCollection(\"animals\");\n\t}\n\n\t@Test\n\tpublic void testMongoInsert() {\n\n\t\tZoo zoo = new Zoo(client);\n\t\tzoo.addAnimal(\"lion\", \"mammal\");\n\n\t\tFindIterable it = client.getDatabase(\"mydb\").getCollection(\"animals\")\n\t\t\t\t.find(new Document(\"name\", \"lion\"));\n\t\tAssert.assertNotNull(it.first());\n\n\t}\n\t\n\t@AfterClass\n\tpublic static void stop(){\n\t\tclient.close();\n\t}\n}\n<\/pre>\nNotice that the IP address of our MongDB database is our Docker machine.<\/p>\n
<\/a>4.3 Running the tests<\/h3>\nTo run our integration tests, we simply need to execute the mvn verify<\/code> command.<\/p>\nRun integration tests<\/em><\/span><\/p>\nmvn verify\n<\/pre>\nWhich will produce these contents:<\/p>\n
Mvn verify output<\/em><\/span><\/p>\nINFO] Building jar: \/Users\/rpau\/workspace\/javacodegeeks\/target\/javacodegeeks-1.0-SNAPSHOT.jar\n[INFO] \n[INFO] --- docker-maven-plugin:0.15.0:start (start) @ javacodegeeks ---\n[INFO] DOCKER> [mongo] : Start container a2a9d37cbbfd\n[INFO] \n[INFO] --- maven-failsafe-plugin:2.19.1:integration-test (integration-test) @ javacodegeeks ---\n\n-------------------------------------------------------\n T E S T S\n-------------------------------------------------------\nRunning javacodegeeks.IntegrationTest\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: Cluster created with settings {hosts=[192.168.99.100:27017], mode=SINGLE, requiredClusterType=UNKNOWN, serverSelectionTimeout='30000 ms', maxWaitQueueSize=500}\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: No server chosen by WritableServerSelector from cluster description ClusterDescription{type=UNKNOWN, connectionMode=SINGLE, all=[ServerDescription{address=192.168.99.100:27017, type=UNKNOWN, state=CONNECTING}]}. Waiting for 30000 ms before timing out\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: Opened connection [connectionId{localValue:1, serverValue:1}] to 192.168.99.100:27017\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: Monitor thread successfully connected to server with description ServerDescription{address=192.168.99.100:27017, type=STANDALONE, state=CONNECTED, ok=true, version=ServerVersion{versionList=[3, 2, 6]}, minWireVersion=0, maxWireVersion=4, maxDocumentSize=16777216, roundTripTimeNanos=1473362}\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: Opened connection [connectionId{localValue:2, serverValue:2}] to 192.168.99.100:27017\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: Closed connection [connectionId{localValue:2, serverValue:2}] to 192.168.99.100:27017 because the pool has been closed.\nTests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.601 sec - in javacodegeeks.IntegrationTest\n\nResults :\n\nTests run: 1, Failures: 0, Errors: 0, Skipped: 0\n\n[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent! The file encoding for reports output files should be provided by the POM property ${project.reporting.outputEncoding}.\n[INFO] \n[INFO] --- docker-maven-plugin:0.15.0:stop (stop) @ javacodegeeks ---\n[INFO] DOCKER> [mongo] : Stop and remove container a2a9d37cbbfd\n[INFO] \n[INFO] --- maven-failsafe-plugin:2.19.1:verify (verify) @ javacodegeeks ---\n<\/pre>\n<\/a>5.Download the source code<\/h2>\n
- \n
- 2.1. Installing docker and docker-machine<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 3. Understanding the commands<\/a><\/dt>\n
- \n
- \n
- 3.1 Creating a machine<\/a><\/dt>\n<\/dl>\n
- \n
- 3.2 Creating an image<\/a><\/dt>\n<\/dl>\n
- \n
- 3.3 Creating a container<\/a><\/dt>\n<\/dl>\n
- \n
- 3.4 Cleaning the environment<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 4.Running integration tests with Maven<\/a><\/dt>\n
- \n
- \n
- 4.1 Maven configuration<\/a><\/dt>\n<\/dl>\n
- \n
- 4.2 Creating the tests<\/a><\/dt>\n<\/dl>\n
- \n
- 4.3 Running the tests<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 5.Download the source code<\/a><\/dt>\n<\/dl>\n<\/div>\n
<\/a>1. Why do we need Docker?<\/h2>\n
<\/a>Docker is a tool to avoid the usual headaches of conflicts, dependencies and inconsistent environments, which is an important problem for distributed applications, where we need to install or upgrade several nodes with the same configuration.<\/p>\nDocker is a container manager, which means that is able to create and execute containers that represent specific runtime environments for your software. In contrast with virtual machines like VirtualBox, Docker uses resource isolation features of the Linux kernel to allow independent \u201ccontainers\u201d to run within a single Linux instance, avoiding the overhead of starting and maintaining virtual machines. A computer with docker can run multiple containers at the same time.<\/p>\n
Therefore, the automation of Docker mainly offers facilities for integration tests and continuous delivery.<\/p>\n
<\/a>2. Machines, Images and Containers<\/h2>\n
In order to use docker, it is important to have clear some vocabulary. Docker distinguishes three important concepts: docker machines, docker images and containers.<\/p>\n
Docker containers are executions of an specific runtime environment. For example, to simulate a machine with an specific database up. These runtime environments are called Docker images, which are the result of executing the set of commands that appear in an specific script-like file called
Dockerfile<\/code>. Therefore, Docker allow having multiple containers of an specific Docker image. These could be compared with the concepts of program and process. Indeed, containers like processes, can be created, stopped, died, or running.<\/p>\nDocker machines are local (and virtual) machines or remote machines(e.g in a cloud such as Amazon AWS or DigitalOcean) with a docker running. Like physical machines, docker machines has an specific IP address. Each docker machine can manage multiple docker images and containers. From our own personal computer, the docker-machine command, allow us connecting to all our docker machines to manage their containers and images.<\/p>\n
<\/a><\/p>\n<\/a>2.1. Installing docker and docker-machine<\/h3>\n
Follow the next steps to install docker and docker machine<\/p>\n
- \n
- Download and install the docker binary file from here<\/a>.Once, you have followed the installation instructions, you should be able to run the following command.
\nDocker installation test<\/em><\/span><\/p>\n$ docker run ubuntu:14.04 \/bin\/echo 'It works!'\nIt works!\n<\/pre>\n<\/li>\n
- Download the Docker Machine binary and update your
PATH<\/code>.If you are running OS X or Linux:
\nUnix Docker Machine installation<\/em><\/span><\/p>\n$ curl -L https:\/\/github.com\/docker\/machine\/releases\/download\/v0.6.0\/docker-machine-`uname -s`-`uname -m` > \/usr\/local\/bin\/docker-machine && \\\nchmod +x \/usr\/local\/bin\/docker-machine\n<\/pre>\n
If you are running Windows with git bash
\nWindows Docker Machine installation<\/em><\/span><\/p>\n$ if [[ ! -d \"$HOME\/bin\" ]]; then mkdir -p \"$HOME\/bin\"; fi && \\\ncurl -L https:\/\/github.com\/docker\/machine\/releases\/download\/v0.6.0\/docker-machine-Windows-x86_64.exe > \"$HOME\/bin\/docker-machine.exe\" && \\\nchmod +x \"$HOME\/bin\/docker-machine.exe\"\n<\/pre>\n
Otherwise, simply use the installer from the Docker official releases<\/a>.<\/li>\n<\/ul>\n
<\/a>3. Understanding the commands<\/h2>\n
There are many docker commands. In fact, if we run simply
docker<\/code> from our terminal, we can see all the available commands.<\/p>\nDocker commands<\/em><\/span><\/p>\n
Commands:\n attach Attach to a running container\n build Build an image from a Dockerfile\n commit Create a new image from a container's changes\n cp Copy files\/folders from a container to a HOSTDIR or to STDOUT\n create Create a new container\n diff Inspect changes on a container's filesystem\n events Get real time events from the server\n exec Run a command in a running container\n export Export a container's filesystem as a tar archive\n history Show the history of an image\n images List images\n import Import the contents from a tarball to create a filesystem image\n info Display system-wide information\n inspect Return low-level information on a container or image\n kill Kill a running container\n load Load an image from a tar archive or STDIN\n login Register or log in to a Docker registry\n logout Log out from a Docker registry\n logs Fetch the logs of a container\n pause Pause all processes within a container\n port List port mappings or a specific mapping for the CONTAINER\n ps List containers\n pull Pull an image or a repository from a registry\n push Push an image or a repository to a registry\n rename Rename a container\n restart Restart a running container\n rm Remove one or more containers\n rmi Remove one or more images\n run Run a command in a new container\n save Save an image(s) to a tar archive\n search Search the Docker Hub for images\n start Start one or more stopped containers\n stats Display a live stream of container(s) resource usage statistics\n stop Stop a running container\n tag Tag an image into a repository\n top Display the running processes of a container\n unpause Unpause all processes within a container\n version Show the Docker version information\n wait Block until a container stops, then print its exit code\n\nRun 'docker COMMAND --help' for more information on a command.\n<\/pre>\n
In this section, we will see how to manage docker machines, how to pull a docker image using an specific docker machine and how to create a container for such docker image.
<\/div> <\/div><\/p>\n<\/a>3.1 Creating a machine<\/h3>\n
First of all, we will list the set of available docker machines with the following command:<\/p>\n
List Docker Machines<\/em><\/span><\/p>\n
docker-machine ls\n<\/pre>\n
In case of not having any machine, we are going to create a new one as follows:<\/p>\n
Docker installation test<\/em><\/span><\/p>\n
docker-machine create --driver virtualbox default\n<\/pre>\n
Notice that in order to create a docker machine, we need to specify a driver, which will determine if it is a virtual machine, in this case virtual box, or if it is a connection to docker running in an external machine.<\/p>\n
<\/a>3.2 Creating an image<\/h3>\n
Docker images are created in an specific docker machine. In order to define the docker machine that we want to use, we need to run the following command:<\/p>\n
Select docker machine<\/em><\/span><\/p>\n
eval \"$(docker-machine env default)\"\n<\/pre>\n
In order to check the effects, list the available docker machines again. At this moment, a new machine should appear with a new IP address (192.168.99.100) and contains an asterisk in the
ACTIVE<\/code> column.<\/p>\nActive Docker Machine<\/em><\/span><\/p>\n
NAME ACTIVE DRIVER STATE URL SWARM\ndefault * virtualbox Running tcp:\/\/192.168.99.100:2376 \n<\/pre>\n
Docker images are the binary files of runtime environments. The contents of a docker image are the result of executing the set of instructions that appear in a plain text file called
Dockerfile<\/code>. However, in order to avoid building docker images from Dockerfiles over and over again, there is an online repository for docker images called Docker Hub<\/a>.<\/p>\nFor example, in order to pull a MongoDB image, we only need to execute the docker pull command as follows:<\/p>\n
Docker pull command<\/em><\/span><\/p>\n
docker pull mongo\n<\/pre>\n
In order to see the installed docker images in our docker machine, use the following command. Notice that a new entry appears with the Mongo image. Each image has a unique identifier of the docker image for our machine called
IMAGE ID<\/code>.<\/p>\nList Docker Images<\/em><\/span><\/p>\n
docker images\n<\/pre>\n
If you are interested to understand how to create a
Dockerfile<\/code>, we strongly recommend follow this<\/a> example.<\/p>\n<\/a>3.3 Creating a container<\/h3>\n
Docker containers are executions of docker images. In order to create a container from an image, we use the command docker run. For example:<\/p>\n
List Docker Images<\/em><\/span><\/p>\n
docker run mongo\n<\/pre>\n
After that, we can check the list of containers, with the following instruction.<\/p>\n
List docker containers<\/em><\/span><\/p>\n
docker ps -a\n<\/pre>\n
Notice that our container has an identifier too, called
CONTAINER ID<\/code>. We will use it later.<\/p>\nThe IP address to connect to this container from our application is the IP of our docker machine (192.168.99.100).<\/p>\n
<\/a>3.4 Cleaning the environment<\/h3>\n
At this point we have downloaded a docker machine and we have started a docker container. In order to stop and remove the container and the image we need to execute the following instructions:<\/p>\n
Stop the container:<\/p>\n
Stop Docker Container<\/em><\/span><\/p>\n
docker stop #containerId\n<\/pre>\n
Remove the container:<\/p>\n
Remove Docker Container<\/em><\/span><\/p>\n
docker rm #containerId\n<\/pre>\n
Remove the docker image:<\/p>\n
Remove Docker Image<\/em><\/span><\/p>\n
docker rmi #imageId\n<\/pre>\n
<\/a>4.Running integration tests with Maven<\/h2>\n
There are different approaches to design integration tests with Docker. In this example, we will design a Maven project, which before executing JUnit tests, it automatically starts a MongoDB Docker container.<\/p>\n
<\/a>4.1 Maven configuration<\/h3>\n
First of all, copy this
pom.xml<\/code> file. We are going to use thedocker-maven-plugin<\/code> to automatically load the defined Docker images and create a container before running the integration tests. In order to support integration tests, we use themaven-failsafe-plugin<\/code>.<\/p>\npom.xml<\/em><\/span><\/p>\n
<project xmlns=\"http:\/\/maven.apache.org\/POM\/4.0.0\" xmlns:xsi=\"http:\/\/www.w3.org\/2001\/XMLSchema-instance\"\n\txsi:schemaLocation=\"http:\/\/maven.apache.org\/POM\/4.0.0 http:\/\/maven.apache.org\/xsd\/maven-4.0.0.xsd\">\n\t<modelVersion>4.0.0<\/modelVersion>\n\n <groupId>javacodegeeks<\/groupId>\n\t<artifactId>javacodegeeks<\/artifactId>\n\t<version>1.0-SNAPSHOT<\/version>\n\t<packaging>jar<\/packaging>\n\n\n <properties>\n <project.build.sourceEncoding>UTF-8<\/project.build.sourceEncoding>\n <project.build.resourceEncoding>UTF-8<\/project.build.resourceEncoding>\n <maven.compile.encoding>UTF-8<\/maven.compile.encoding>\n <\/properties>\n\n <build>\n <plugins>\n \n <plugin>\n <artifactId>maven-compiler-plugin<\/artifactId>\n <version>2.1<\/version>\n <configuration>\n <source>1.8<\/source>\n <target>1.8<\/target>\n <encoding>UTF-8<\/encoding>\n <\/configuration>\n <\/plugin>\n <plugin>\n <groupId>org.apache.maven.plugins<\/groupId>\n <artifactId>maven-failsafe-plugin<\/artifactId>\n <version>2.19.1<\/version>\n <configuration>\n <includes>\n <include>**\/IntegrationTest.java<\/include>\n <\/includes>\n <\/configuration>\n <executions>\n <execution>\n <id>integration-test<\/id>\n <goals>\n <goal>integration-test<\/goal>\n <\/goals>\n <\/execution>\n <execution>\n <id>verify<\/id>\n <goals>\n <goal>verify<\/goal>\n <\/goals>\n <\/execution>\n <\/executions>\n <\/plugin>\n <!-- Tell surefire to skip test, we are using the failsafe plugin -->\n <plugin>\n <groupId>org.apache.maven.plugins<\/groupId>\n <artifactId>maven-surefire-plugin<\/artifactId>\n <version>2.10<\/version>\n <configuration>\n <skip>true<\/skip>\n <\/configuration>\n <\/plugin>\n <plugin>\n <groupId>io.fabric8<\/groupId>\n <artifactId>docker-maven-plugin<\/artifactId>\n <version>0.15.0<\/version>\n <configuration>\n <logDate>default<\/logDate>\n <autoPull>true<\/autoPull>\n <dockerHost>tcp:\/\/192.168.99.100:2376<\/dockerHost>\n <certPath>${user.home}\/.docker\/machine\/certs\/<\/certPath>\n <images>\n <image>\n <name>mongo<\/name>\n <run>\n <ports>\n <port>27017:27017<\/port>\n <\/ports> \n <\/run>\n <\/image>\n \n <\/images>\n <\/configuration>\n <!-- Hooking into the lifecycle -->\n <executions>\n <execution>\n <id>start<\/id>\n <phase>pre-integration-test<\/phase>\n <goals>\n <goal>start<\/goal>\n <\/goals>\n <\/execution>\n <execution>\n <id>stop<\/id>\n <phase>post-integration-test<\/phase>\n <goals>\n <goal>stop<\/goal>\n <\/goals>\n <\/execution>\n <\/executions>\n <\/plugin>\n <\/plugins>\n <\/build>\n <dependencies>\n <dependency>\n\t <groupId>org.mongodb<\/groupId>\n\t <artifactId>mongo-java-driver<\/artifactId>\n\t <version>3.2.2<\/version>\n <\/dependency>\n <dependency>\n <groupId>junit<\/groupId>\n <artifactId>junit<\/artifactId>\n <version>4.12<\/version>\n <scope>test<\/scope>\n <\/dependency>\n <\/dependencies>\n <\/project>\n<\/pre>\n<\/a>4.2 Creating integration tests<\/h3>\n
Integration tests are executed after creating a MongoDB container by the
maven-docker-plugin<\/code>. We are going to create a test to validate the followingZoo<\/code> component, which only has one operation calledaddAnimal<\/code> that inserts an animal to MongoDB.[ulp id=’6PVIvOz3kDbYmNRn’]<\/p>\nZoo.java<\/em><\/span><\/p>\n
package javacodegeeks;\n\nimport org.bson.Document;\n\nimport com.mongodb.MongoClient;\n\npublic class Zoo {\n\n\tprivate MongoClient client;\n\n\tpublic Zoo(MongoClient client) {\n\t\tthis.client = client;\n\t}\n\n\tpublic void addAnimal(String name, String type) {\n\t\tDocument doc = new Document(\"name\", \"lion\").append(\"type\", \"mammal\");\n\t\tclient.getDatabase(\"mydb\").getCollection(\"animals\").insertOne(doc);\n\t}\n}\n<\/pre>\nTo test the
Zoo<\/code> component, we just validate, with an empty database, that after invoking theaddAnimal<\/code> operation, MongoDB contains a new animal.<\/p>\nIntegrationTest.java<\/em><\/span><\/p>\n
package javacodegeeks;\n\nimport org.bson.Document;\nimport org.junit.AfterClass;\nimport org.junit.Assert;\nimport org.junit.BeforeClass;\nimport org.junit.Test;\nimport com.mongodb.MongoClient;\nimport com.mongodb.client.FindIterable;\nimport com.mongodb.client.MongoDatabase;\n\npublic class IntegrationTest {\n\n\tprivate static MongoClient client;\n\n\t@BeforeClass\n\tpublic static void start() {\n\t\tclient = new MongoClient(\"192.168.99.100\");\n\t\tMongoDatabase db = client.getDatabase(\"mydb\");\n\t\tdb.createCollection(\"animals\");\n\t}\n\n\t@Test\n\tpublic void testMongoInsert() {\n\n\t\tZoo zoo = new Zoo(client);\n\t\tzoo.addAnimal(\"lion\", \"mammal\");\n\n\t\tFindIterable it = client.getDatabase(\"mydb\").getCollection(\"animals\")\n\t\t\t\t.find(new Document(\"name\", \"lion\"));\n\t\tAssert.assertNotNull(it.first());\n\n\t}\n\t\n\t@AfterClass\n\tpublic static void stop(){\n\t\tclient.close();\n\t}\n}\n<\/pre>\nNotice that the IP address of our MongDB database is our Docker machine.<\/p>\n
<\/a>4.3 Running the tests<\/h3>\n
To run our integration tests, we simply need to execute the
mvn verify<\/code> command.<\/p>\nRun integration tests<\/em><\/span><\/p>\n
mvn verify\n<\/pre>\n
Which will produce these contents:<\/p>\n
Mvn verify output<\/em><\/span><\/p>\n
INFO] Building jar: \/Users\/rpau\/workspace\/javacodegeeks\/target\/javacodegeeks-1.0-SNAPSHOT.jar\n[INFO] \n[INFO] --- docker-maven-plugin:0.15.0:start (start) @ javacodegeeks ---\n[INFO] DOCKER> [mongo] : Start container a2a9d37cbbfd\n[INFO] \n[INFO] --- maven-failsafe-plugin:2.19.1:integration-test (integration-test) @ javacodegeeks ---\n\n-------------------------------------------------------\n T E S T S\n-------------------------------------------------------\nRunning javacodegeeks.IntegrationTest\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: Cluster created with settings {hosts=[192.168.99.100:27017], mode=SINGLE, requiredClusterType=UNKNOWN, serverSelectionTimeout='30000 ms', maxWaitQueueSize=500}\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: No server chosen by WritableServerSelector from cluster description ClusterDescription{type=UNKNOWN, connectionMode=SINGLE, all=[ServerDescription{address=192.168.99.100:27017, type=UNKNOWN, state=CONNECTING}]}. Waiting for 30000 ms before timing out\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: Opened connection [connectionId{localValue:1, serverValue:1}] to 192.168.99.100:27017\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: Monitor thread successfully connected to server with description ServerDescription{address=192.168.99.100:27017, type=STANDALONE, state=CONNECTED, ok=true, version=ServerVersion{versionList=[3, 2, 6]}, minWireVersion=0, maxWireVersion=4, maxDocumentSize=16777216, roundTripTimeNanos=1473362}\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: Opened connection [connectionId{localValue:2, serverValue:2}] to 192.168.99.100:27017\nmay 15, 2016 6:11:10 PM com.mongodb.diagnostics.logging.JULLogger log\nINFORMACI\u00d3N: Closed connection [connectionId{localValue:2, serverValue:2}] to 192.168.99.100:27017 because the pool has been closed.\nTests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.601 sec - in javacodegeeks.IntegrationTest\n\nResults :\n\nTests run: 1, Failures: 0, Errors: 0, Skipped: 0\n\n[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent! The file encoding for reports output files should be provided by the POM property ${project.reporting.outputEncoding}.\n[INFO] \n[INFO] --- docker-maven-plugin:0.15.0:stop (stop) @ javacodegeeks ---\n[INFO] DOCKER> [mongo] : Stop and remove container a2a9d37cbbfd\n[INFO] \n[INFO] --- maven-failsafe-plugin:2.19.1:verify (verify) @ javacodegeeks ---\n<\/pre>\n<\/a>5.Download the source code<\/h2>\n
- Download the Docker Machine binary and update your
- 5.Download the source code<\/a><\/dt>\n<\/dl>\n<\/div>\n
- 4.3 Running the tests<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 4.2 Creating the tests<\/a><\/dt>\n<\/dl>\n
- 4.Running integration tests with Maven<\/a><\/dt>\n
- 3.4 Cleaning the environment<\/a><\/dt>\n<\/dl>\n<\/dd>\n
- 3.3 Creating a container<\/a><\/dt>\n<\/dl>\n
- 3.2 Creating an image<\/a><\/dt>\n<\/dl>\n
- 3. Understanding the commands<\/a><\/dt>\n