feat: support private registry host (#28)

This pull request adds support for non-default docker hosts (such as self-hosted registries or services like Amazon ECR). It introduces an optional environment variable DOCKER_REGISTRY to denote the URL of the registry. If this variable is left blank, the default registry of the docker client (probably Docker Hub) will be used.

README.md

@@ -16,7 +16,10 @@ Set of [semantic-release](https://github.com/semantic-release/semantic-release)
 ```json
 {
   "release": {
-    "verifyConditions": "semantic-release-docker",
+    "verifyConditions": {
+      "path": "semantic-release-docker",
+      "registryUrl": "docker.io"
+    },
     "publish": {
       "path": "semantic-release-docker",
       "name": "username/imagename"
@@ -29,7 +32,7 @@ Set of [semantic-release](https://github.com/semantic-release/semantic-release)
 
 Your credentials have to be configured with the environment variables `DOCKER_USERNAME` and `DOCKER_PASSWORD`.
 
-In addition, you need to specify the name of the image as the `name` setting.
+In addition, you need to specify the name of the image as the `name` setting in the publish step. If you need to specify a custom docker registry URL, add it as the `registryUrl` setting in the verifyConditions step.
 
 ## Plugins
 

lib/verify.js

@@ -7,9 +7,18 @@ module.exports = async (pluginConfig, { logger }) => {
     }
   }
   try {
-    await execa('docker', ['login', '-u=' + process.env.DOCKER_USERNAME, '-p=' + process.env.DOCKER_PASSWORD], {
-      stdio: 'inherit',
-    })
+    await execa(
+      'docker',
+      [
+        'login',
+        pluginConfig.registryUrl || '',
+        '-u=' + process.env.DOCKER_USERNAME,
+        '-p=' + process.env.DOCKER_PASSWORD,
+      ],
+      {
+        stdio: 'inherit',
+      }
+    )
   } catch (err) {
     throw new Error('docker login failed')
   }