Terraform import when switching provider

For historical reasons, we inherited a terraform setup and state file with some custom provider. This made the code very unintuitive, since there were two providers doing the same thing mixed together.

Approach

1. Backup original statefile
2. Change code to new provider (this is manual and tedious)

3. Get list of items of statefile

   # this requires the state to be in a clean folder, so it's not affected by the tf code
   terraform state list|grep -v ^data|sort > resources-tfstate.list
   cat terraform.tfstate |jq '.resources[] | select(.mode == "managed")' > managed.tfstate
   
   while read l; do
       TYPE=`echo $l|sed 's/^\(.*\)\.\(.*\)$/\1/'`
       NAME=`echo $l|sed 's/^\(.*\)\.\(.*\)$/\2/'`
       echo "$TYPE.$NAME" # terraform import argument
       echo "cat managed.tfstate | jq 'select(.type == \"$TYPE\") | select(.name == \"$NAME\") | .instances[].attributes'"
   done < resources-tfstate.list
   

4. Get list of resources defined in the code

   # this needs to be run in the root of the tf code dir
   grep -r '^resource\ '|grep '\.tf'|sort > resources-tf.list
   
   # The following only works if you did terraform fmt -recursive
   while read l; do
       TYPE=`echo $l|sed 's/^.*:resource "\(.*\)" "\(.*\)" {$/\1/'`
       NAME=`echo $l|sed 's/^.*:resource "\(.*\)" "\(.*\)" {$/\2/'`
       echo "$TYPE.$NAME" # terraform import argument
   done < resources-tf.list
   

5. Manually map items onto each other

   terraform import TYPE.NAME ENV.ID