📝 Add instructions to run batch container

containers/README.md

@@ -14,6 +14,41 @@
 # serratus-prometheus
 ```
 
+## Local pipeline
+Serratus provides a simplified image for local development. This is a good place to start.
+
+First, build the `serratus-batch` _image_. From this directory:
+`docker build -t serratus-batch -f ./serratus-batch/Dockerfile .`
+* `-t serratus-batch` - Tag the image so we can reference it later
+* `-f ./serratus-batch/Dockerfile` - Use the indicated Dockerfile to build the image
+* `.` - Root the build at the current directory
+
+Now that you've got the _image_ built, you can run a new _container_ from that image. `serratus-batch` is a tools container, which means it is expected to run, and then exit. It writes output data to AWS s3.
+
+For s3 access, you'll need to set up an IAM keypair. Set the following environment variables - they'll be passed to the running _container_.
+```
+export AWS_ACCESS_KEY_ID="AKIA...."
+export AWS_SECRET_ACCESS_KEY="secret_key_here"
+```
+
+Then, run the _container_
+`docker run --rm -ti -e AWS_ACCESS_KEY_ID -e AWS_SECRET_ACCESS_KEY serratus-batch run <SRA> <Index>`
+* `--rm` - Remove the container after it exits
+* `-ti` - Hook up a TTY and Interactive mode. tl;dr - Get output on your screen, kill it with Ctrl+C
+* `-e ...` - Forward your AWS credentials to the container
+* `serratus-batch` - This is the image to use for the new container. Reference by the tag we set when we built the image
+* `run <SRA> <Index>` - This is the command that will be executed in the container
+
+Tips:
+* To poke around the container, substitute `/bin/bash` for `run ...`. That will run the container and drop you into a bash shell, where you can run the pipeline piece-by-piece yourself.
+* To save a pre-fetched accession for experimentation:
+  1. Run with `/bin/bash`
+  2. `prefetch <SRA>`
+  3. From another shell, `docker ps` to find your container name. Then `docker commit <name> docker-batch:<pick_a_tag_name>`
+  4. Substitute `docker-batch:tag` as the image for `docker run`, and `/bin/bash` as the command
+  5. Manually run the pipeline. Copy commands from `serratus-batch/run` to start out.
+* To build a tagged image with a pre-downloaded index, follow the above steps. Instead of `prefetch <SRA>`, run `aws s3 cp ...` (copy from `run.sh`), and commit the result
+
 ## Build all containers for serratus
 Instructions for EC2/Amazon Linux
 ```