Building Images Using Apis

In the previous recipe, we explored a few actions on Docker images using APIs. In this recipe, we will build a Docker image using the /build API. Here is the /build API snippet from Swagger Editor:

How to do it…

1. Begin by cloning the https://github.com/docker-cookbook/apache2 repository, as follows:

$ git clone https://github.com/docker-cookbook/apache2

This repository contains the Dockerfile to bundle an apache2 service; listed here is the content of the Dockerfile :

1. Let’s create the build context by bundling the content of the cloned apache2 repository as a tar file, as demonstrated here:

$ cd apache2
$ tar cvf /tmp/apache2.tar *

1. Continue on to build the Docker image using the /build API:

$ curl -X POST \
           -H "Content-Type:application/tar" \
           --data-binary '@/tmp/apache2.tar' \
           --unix-socket /var/run/docker.sock \
           http:/build

While the build is in progress, you will receive the build logs as a series of JSON messages. Once the build is successfully completed, you will get a JSON message like this one:

{"stream":"Successfully built 3c6f5044386d\n"}

In the preceding JSON message, 3c6f5044386d is the ID of the image we just built using the /build API.

How it works…

In this recipe, we bundled the build context as a tar file and sent it to the Docker engine as part of the /build API call. The Docker engine uses the build context and the Dockerfile in the build context to build the Docker image.

There’s more…

1. In this recipe, we did not specify any repository or tag name, and hence the image is created without any repository or tag name, as shown here:

$ curl -s --unix-socket /var/run/docker.sock \
                 http:/images/json | jq ".[0].RepoTags"
[
"<none>:<none>"
]

Of course, you can now tag the image with the appropriate repository and tag name using the /images/{name}/tag API. Here is the help document snipped from the Swagger editor:

Alternatively, you can bundle the image with the repository name during the build time using the t parameter, as demonstrated here:

$ curl -X POST \
           -H "Content-Type:application/tar" \
           --data-binary '@/tmp/apache2.tar' \
           --unix-socket /var/run/docker.sock \
           http:/build?t=apache2:usingapi

The tag name is optional and if no tag name is specified, the Docker build engine will assume the tag name latest .

1. You can also create an image from a container using the following API:

Here is an example of committing an image from a container ID 4aaec8980c43 :

See also

Each API endpoint can have different inputs to control the operations. For more details, visit the documentation on the Docker website at https://docs.docker.com/engine/api/latest/.