Allow arbitrary extra args to be passed to docker build and dockerized pip install steps

README.md

@@ -270,6 +270,18 @@ custom:
           - --compile
 ```
 
+### Extra Docker arguments
+
+You can specify extra arguments to be passed to [docker build](https://docs.docker.com/engine/reference/commandline/build/) during the build step, and [docker run](https://docs.docker.com/engine/reference/run/) during the dockerized pip install step:
+
+```yaml
+custom:
+  pythonRequirements:
+    dockerizePip: true
+    dockerBuildCmdExtraArgs: ["--build-arg", "MY_GREAT_ARG=123"]
+    dockerRunCmdExtraArgs: ["-v", "${env:PWD}:/my-app"]
+```
+
 
 ### Customize requirements file name
 [Some `pip` workflows involve using requirements files not named

index.js

@@ -48,6 +48,8 @@ class ServerlessPythonRequirements {
         dockerImage: null,
         dockerFile: null,
         dockerEnv: false,
+        dockerBuildCmdExtraArgs: [],
+        dockerRunCmdExtraArgs: [],
         useStaticCache: false,
         useDownloadCache: false,
         cacheLocation: false,

lib/docker.js

@@ -25,11 +25,21 @@ function dockerCommand(options) {
 /**
  * Build the custom Docker image
  * @param {string} dockerFile
+ * @param {string[]} extraArgs
  * @return {string} The name of the built docker image.
  */
-function buildImage(dockerFile) {
+function buildImage(dockerFile, extraArgs) {
   const imageName = 'sls-py-reqs-custom';
-  const options = ['build', '-f', dockerFile, '-t', imageName, '.'];
+  const options = ['build', '-f', dockerFile, '-t', imageName];
+
+  if (Array.isArray(extraArgs)) {
+    options.push(...extraArgs);
+  } else {
+    throw new Error('dockerRunCmdExtraArgs option must be an array');
+  }
+
+  options.push('.');
+
   dockerCommand(options);
   return imageName;
 }

lib/pip.js

@@ -180,7 +180,10 @@ function installRequirements(targetFolder, serverless, options) {
       serverless.cli.log(
         `Building custom docker image from ${options.dockerFile}...`
       );
-      dockerImage = buildImage(options.dockerFile);
+      dockerImage = buildImage(
+        options.dockerFile,
+        options.dockerBuildCmdExtraArgs
+      );
     } else {
       dockerImage = options.dockerImage;
     }
@@ -259,6 +262,13 @@ function installRequirements(targetFolder, serverless, options) {
       // Use same user so --cache-dir works
       dockerCmd.push('-u', getDockerUid(bindPath));
     }
+
+    if (Array.isArray(options.dockerRunCmdExtraArgs)) {
+      dockerCmd.push(...options.dockerRunCmdExtraArgs);
+    } else {
+      throw new Error('dockerRunCmdExtraArgs option must be an array');
+    }
+
     dockerCmd.push(dockerImage);
   }