Add ability to customize envrc settings via .envr.localHEADmaster

This allows, for example, to easily run a different major Postgres version.

1 files changed, 23 insertions, 1 deletions

diff --git a/README b/README
index a4aa7c0..379b245 100644
--- a/README
+++ b/README
@@ -19,4 +19,26 @@ Then you can run a Postgres server with `./ppq start`.
 
 All Postgres client programs (like `psql`, `pg_restore` etc) are
 available and environment variables like `PGUSER` and `PGHOST` are set
-up to ensure it will talk to the local Postgres server automatically.
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+up to ensure it will talk to the local Postgres server automatically.
+
+
+Customizing the project
+-----------------------
+
+The `.envrc` file loads a `.envrc.local` if it exists.  Here, you can
+override any environment variables you want.  The following environment
+variables can be overridden:
+
+  PPQ_POSTGRES_VERSION - the major Postgres version to use
+  PPQ_POSTGRES_DIR - The *absolute path* to the directory that holds that data dir
+  PPQ_POSTGRES_DATA_DIR - The *absolute path* to the PostgreSQL data directory
+
+Note that you can use direnv's expand_path function to make a relative
+path absolute.
+
+The `ppq.sh` script will also execute `${PPQ_POSTGRES_DIR}/prepare.sql`
+when preparing the database via initdb.
+
+If you want to add `postgresql.conf` settings, you can create a file
+called `${PPQ_POSTGRES_DIR}/postgresql_overrides.conf` and it will be
+loaded by `postgresql.conf`.
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