From e92919fe3f19987f201e3664b1381cc97c1e45cf Mon Sep 17 00:00:00 2001
From: Anselme Goetschmann <ang@open.ch>
Date: Fri, 18 May 2018 11:16:30 +0200
Subject: [PATCH] Update README

---
 .gitignore | 35 ++++++++++++++++++++++++++
 README.md  | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 106 insertions(+), 1 deletion(-)

diff --git a/.gitignore b/.gitignore
index e69de29..5d5ea4f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -0,0 +1,35 @@
+!Build/
+.last_cover_stats
+/META.yml
+/META.json
+/MYMETA.*
+*.o
+*.pm.tdy
+*.bs
+
+# Devel::Cover
+cover_db/
+
+# Devel::NYTProf
+nytprof.out
+
+# Dizt::Zilla
+/.build/
+
+# Module::Build
+_build/
+Build
+Build.bat
+
+# Module::Install
+inc/
+
+# ExtUtils::MakeMaker
+/blib/
+/_eumm/
+/*.gz
+/Makefile
+/Makefile.old
+/MANIFEST.bak
+/pm_to_blib
+/*.zip
\ No newline at end of file
diff --git a/README.md b/README.md
index 0e37d58..49bd48f 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,73 @@
 # InfluxDB Schema Updater
 
-The influxdb-schema updater is a small DevOps tool to manage the schema of a [InfluxDB](https://github.com/influxdata/influxdb) with a set of configuration files.
+The InfluxDB schema updater is a small DevOps tool to manage the schema of an [InfluxDB](https://github.com/influxdata/influxdb) instance with a set of configuration files. 
+
+# SYNOPSIS
+
+`influxdb-schema-updater [--help] [--dryrun] [--diff] [--force] [--config <schema_location>] [--url <url>]`
+
+# OPTIONS
+
+- **--help**
+
+    Print a help message and exit.
+
+- **--dryrun**
+
+    Print the changes which would be applied in normal mode.
+
+- **--diff**
+
+    Print the InfluxQL queries instead of executing them.
+
+- **--force**
+
+    Apply the changes which were prevented in normal mode.
+
+- **--config**
+
+    The directory where the schema files are located. Default is /etc/influxdb/schema/.
+
+- **--url**
+
+    The url where the InfluxDB HTTP API is reachable. Default is localhost:8086.
+
+# DESCRIPTION
+
+This tool compares the databases, retention policies (RPs) and continuous queries (CQs) found in the `<schema_location>` directory to the ones in the InfluxDB instance reachable at `<url>`. If there is a difference, InfluxDB will be updated. Some changes like deleting a database are skipped when the `--force` flag is not set.
+
+The exit code is 0 if and only if every required update has been executed successfully.
+
+The `<schema_location>` directory should have the following structure:
+
+```
+db/
+    <db_file1>
+    <db_file2>
+    ...
+cq/
+    <cq_file1>
+    <cq_file2>
+        ...
+```
+
+The files in `db/` contain `CREATE` queries for databases followed by their their RPs, for example:
+
+```
+CREATE DATABASE test WITH DURATION 100d REPLICATION 1 SHARD DURATION 2w NAME rp1;
+CREATE RETENTION POLICY rp2 ON test DURATION 260w REPLICATION 1 SHARD DURATION 12w;
+
+CREATE DATABASE test2;
+CREATE RETENTION POLICY rp1 ON test2 DURATION 100d REPLICATION 1 SHARD DURATION 2w;
+CREATE RETENTION POLICY rp2 ON test2 DURATION 260w REPLICATION 1 SHARD DURATION 12w;
+CREATE RETENTION POLICY rp3 ON test2 DURATION INF REPLICATION 1 SHARD DURATION 260w;
+```
+
+The files in `cq/` contain CQs usually corresponding to the databases declared in the file with the same name in `db/`, for example:
+
+```
+CREATE CONTINUOUS QUERY cq1 ON test RESAMPLE EVERY 5m FOR 10m BEGIN SELECT LAST(a) AS b, c INTO test.rp2.m FROM test.rp1.m GROUP BY time(5m) END;
+
+CREATE CONTINUOUS QUERY cq1 ON test2 RESAMPLE EVERY 30m FOR 1h BEGIN SELECT LAST(a) AS b, c INTO test2.rp2.m FROM test2.rp1.m GROUP BY time(30m) END;
+CREATE CONTINUOUS QUERY cq2 ON test2 RESAMPLE EVERY 1d FOR 2d BEGIN SELECT LAST(a) AS b, c INTO test2.rp3.m FROM test2.rp2.m GROUP BY time(1d) END;
+```