Development Environment

Terraform based code to setup a development environment for hacking Haskell code in general, and projects using IOHK's infrastructure in particular. The VM will be configured to use:

• Vanilla Emacs for editing code, with lsp-mode using lsp-haskell and haskell-language-server,
• nix for dependencies management and building Haskell code, with nix-shell providing the proper environment for emacs' LSP,
• cachix configuration to speed up build,
• direnv to provide a per-directory environment that will trigger entering nix.

Install

GCP

terraform and packer require access to GCP resources which is controlled by a Service account configuration.

Assuming one has "admin" access to a GCP project, the following steps will create a service account, set the needed permissions and retriev a key file which can then be used to configure the scripts:

Create the service account:

$ gcloud iam service-accounts create hydra-poc-builder

Add needed permissions:

$ gcloud projects add-iam-policy-binding iog-hydra --member "serviceAccount:[email protected]" --role "roles/compute.admin"
$ gcloud projects add-iam-policy-binding iog-hydra --member "serviceAccount:[email protected]" --role "roles/iam.serviceAccountUser"
$ gcloud projects add-iam-policy-binding iog-hydra --member "serviceAccount:[email protected]" --role "roles/compute.instanceAdmin.v1"
$ gcloud projects add-iam-policy-binding iog-hydra --member "serviceAccount:[email protected]" --role "roles/storage.objectAdmin"

The service account must be able to create various compute instances, to modify the state which is stored inside a Google Storage bucket, and to impersonate a service account user (unsure what this really means...).

Create service account's key file:

$ gcloud iam service-accounts keys create hydra-poc-builder.json --iam-account [email protected]

Building the base image

This is not mandatory and can be changed by editing the image = iog-hydra-xxxx parameter in compute.tf but this code also provides Packer script to build a base image:

$ cd packer
$ packer build build.json -var 'gcp_account_file=xxx' -var 'gcp_project_id=zzz'
... <takes some time>

The builder depends on two user variables that tells packer how to authenticate to GCP and which project to run the builder in. This base image will be named iog-hydra-<timestamp> and available for use once the build finishes. The configuration of the image is done using script build-env.sh.

Deploying the VM

Initialise Terraform:

$ terraform init

Create a compute.tfvars containing a single variable for cachix_authentication token. It can be left empty, in which no additional cachix configuration will be done when the VM spins up.

Update the ssh_keys file with public keys that will be allowed to log into the VM, prefixing each key with curry or root depending on whether one wants to provide normal user or super-user access to the VM. Note the user curry will automatically be given sudo rights by the packer builder.

Then create a deployment plan and apply it:

$ terraform plan -out vm.plan  -var-file compute.tfvars
$ terraform apply vm.plan
... <takes some more time>

Apply complete! Resources: 2 added, 0 changed, 0 destroyed.

Outputs:

instance_id = https://www.googleapis.com/compute/v1/projects/xxx
instance_ip = X.Y.Z.T

Snapshots

Deploying a VM from scratch takes a while, depending on the current set of projects configured (see configure.sh). To speed things up there's provision to replace the VM's image-based disk with a snapshot-based disk, and to create snapshots from a running VM.

Assuming VM is running, creating a snapshot is as simple as :

$ scripts/snapshot.sh

Using an existing snapshot requires setting the use_snapshot in terraform to 1:

$ terraform apply -var-file=dev-vm.tfvars -var use_snapshot=1 -auto-approve

Using the VM

Then one should be able to log into the VM as user curry, start tmux and emacs, and then hack some stuff.

To log in to the VM:

$ scripts/login.sh curry@haskell-dev-vm-1

Troubleshooting

Most issues boil down to authentication or authorisation problems.

Packer times out while trying to build an image

googlecompute: output will be in this color.

==> googlecompute: Checking image does not exist...
==> googlecompute: Creating temporary rsa SSH key for instance...
==> googlecompute: Using image: ubuntu-2004-focal-v20210112
==> googlecompute: Creating instance...
    googlecompute: Loading zone: europe-west4-a
    googlecompute: Loading machine type: n1-standard-1
    googlecompute: Requesting instance creation...
    googlecompute: Waiting for creation operation to complete...
==> googlecompute: Error creating instance: time out while waiting for instance to create
Build 'googlecompute' errored after 5 minutes 6 seconds: Error creating instance: time out while waiting for instance to create

==> Wait completed after 5 minutes 6 seconds

==> Some builds didn't complete successfully and had errors:
--> googlecompute: Error creating instance: time out while waiting for instance to create

==> Builds finished but no artifacts were created.

The build.json definition uses a service account which is passed through gcp_account_file variable. The service account probably is missing some permissions.

Cannot log in to the VM using scripts/login.sh

This script uses GOOGLE_APPLICATION_CREDENTIALS environment variable to activate the corresponding service account and use gcloud compute ssh to log in. Check authorizations of the service account.

Cannot log in to the VM using plain ssh

• The set of authorized public keys is defined in the ssh_keys file: Check there is a private key corresponding to this public key. Changing the ssh_keys file and re-running terraform apply does not entail recreation of the VM so it's pretty fast
• If ssh-agent is running, check that a private key corresponding to an authorized public key is loaded with ssh-add -l

Terraform fails to run scripts/configure.sh on the VM

Terraform relies on plain SSH to connect to the VM, so this can be caused by the same problems as the previous issue

Pushing or pulling to/from GitHub fails

• When log in to the VM, ensures agent forwarding (ssh -A ...) is set and that ssh-agent is running. Agent forwarding is enabled by default in the scripts/login.sh.
• The ordering of keys loaded in ssh-agent matters: Git will try each key in order until it succeeds to access [email protected], and then will try to access the repository. If a key is known to GitHub but does not have access to the repository, then git will fail without given much information. Check the order using ssh-add -l and fix it in case of doubts

Some keyboard combinations for Emacs/Vim/Tmux are not available

This comes from the terminal and/or OS configuration which might capture certain combinations before sending them to the remote host.