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=head1 Name
sqitch-authentication - Guide to using database authentication credentials with Sqitch
=head1 Description
For database engines that require authentication, Sqitch supports a number
of credential-specification options, and searches for them in a specific
sequence. These searches are performed in two parts: a search for a username
and a search for a password.
=head1 Usernames
Sqitch searches for usernames sequentially, using the first value it finds.
Any of these approaches may be used to specify a username, in this order:
=over
=item 1. In the C<$SQITCH_USERNAME> environment variable
=item 2. Via the C<--db-username> option
=item 3. In the deploy target URI; this is the preferred option
=item 4. In an engine-specific environment variable or configuration
=back
Naturally, this last option varies by database engine. The details are as
follows:
=over
=item PostgreSQL, YugabyteDB, CockroachDB
The Postgres, Yugabyte, and Cockroach engines use the C<PGUSER> environment
variable, if set. Otherwise, it uses the system username.
=item MySQL
For MySQL, if the L<MySQL::Config> module is installed, usernames and
passwords can be specified in the
L<F</etc/my.cnf> and F<~/.my.cnf> files|https://dev.mysql.com/doc/refman/5.7/en/password-security-user.html>.
These files must limit access only to the current user (C<0600>). Sqitch will
look for a username and password under the C<[client]> and C<[mysql]>
sections, in that order.
=item Oracle
Oracle provides no default to search for a username.
=item Vertica
The Vertica engine uses the C<VSQL_USER> environment variable, if set.
Otherwise, it uses the system username.
=item Firebird
The Firebird engine uses the C<ISC_USER> environment variable, if set.
=item Exasol
Exasol provides no default to search for a username.
=item Snowflake
The Snowflake engine uses the C<SNOWSQL_USER> environment variable, if set.
Next, it looks in the
L<F<~/.snowsql/config> file|https://docs.snowflake.com/en/user-guide/snowsql-start.html#snowsql-config-file>
and use the default C<connections.username> value. Otherwise, it uses the
system username.
=back
=head1 Passwords
You may have noticed that Sqitch has no C<--password> option. This is
intentional. It's generally not a great idea to specify a password on the
command-line: from there, it gets logged to your command history and is easy
to extract by anyone with access to your system. So you might wonder how to
specify passwords so that Sqitch an successfully deploy to databases that
require passwords. There are four approaches, in order from most- to
least-recommended:
=over
=item 1. Avoid using a password at all
=item 2. Use a database engine-specific password file
=item 3. Use the C<$SQITCH_PASSWORD> environment variable
=item 4. Include the password in the deploy target URI
=back
Each is covered in detail in the sections below.
=head2 Don't use Passwords
Of course, the best way to protect your passwords is not to use them at all.
If your database engine is able to do passwordless authentication, it's worth
taking the time to make it work, especially on your production database
systems. Some examples:
=over
=item PostgreSQL
PostgreSQL supports a number of
L<authentication methods|https://www.postgresql.org/docs/current/static/auth-methods.html>,
including the passwordless L<SSL certificate|https://www.postgresql.org/docs/current/static/auth-methods.html#AUTH-CERT>, L<GSSAPI|https://www.postgresql.org/docs/current/static/auth-methods.html#GSSAPI-AUTH>, and, for local connections,
L<peer authentication|https://www.postgresql.org/docs/current/static/auth-methods.html#AUTH-PEER>.
=item MySQL
MySQL supports a number of
L<authentication methods|https://dev.mysql.com/doc/internals/en/authentication-method.html>,
plus L<SSL authentication|https://dev.mysql.com/doc/internals/en/ssl.html>.
=item Oracle
Oracle supports a number of
L<authentication methods|https://docs.oracle.com/cd/B19306_01/network.102/b14266/authmeth.htm#BABCGGEB>,
including
L<SSL authentication|https://docs.oracle.com/cd/B19306_01/network.102/b14266/authmeth.htm#i1009722>,
L<third-party authentication|https://docs.oracle.com/cd/B19306_01/network.102/b14266/authmeth.htm#i1009853>,
and, for local connections,
L<OS authentication|https://docs.oracle.com/cd/B19306_01/network.102/b14266/authmeth.htm#i1007520>.
=item Vertica
Vertica supports a number of
L<authentication methods|https://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/AdministratorsGuide/Security/ClientAuth/SupportedClientAuthenticationMethods.htm>
including the passwordless L<TLS authentication|https://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/AdministratorsGuide/Security/ClientAuth/ConfiguringTLSAuthentication.htm>,
L<GSS authentication|https://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/AdministratorsGuide/Security/ClientAuth/Kerberos/ImplementingKerberosAuthentication.htm>,
and, for local connections,
L<ident authentication|https://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/AdministratorsGuide/Security/ClientAuth/ConfiguringIdentAuthentication.htm>.
=item Firebird
Firebird supports passwordless authentication only via
L<trusted authentication|https://www.firebirdsql.org/manual/qsg2-config.html>
for local connections.
=item Exasol
Exasol doesn't seem to support password-less authentication at this time,
though there is support for
L<Authentication using OpenID|https://docs.exasol.com/sql/create_user.htm#Authenti4>.
To use it with Sqitch, include C<AUTHMETHOD=refreshtoken> in the target URI
query string, e.g.,
  db:exasol://sys:exasol@localhost:8563/?Driver=Exasol&AUTHMETHOD=refreshtoken
=item Snowflake
Snowflake does not support password-less authentication, but does support
key-pair authentication. Follow
L<the instructions|https://docs.snowflake.com/en/user-guide/snowsql-start.html#using-key-pair-authentication>
to create a key pair, then set the following variables in the F<~/.snowsql/config>
file:
  authenticator = SNOWFLAKE_JWT
  private_key_path = "path/to/privatekey.p8"
To connect, set the C<$SNOWSQL_PRIVATE_KEY_PASSPHRASE> environment variable to
the passphrase for the private key, and add these parameters to the query part
of your connection URI:
=over
=item * C<authenticator=SNOWFLAKE_JWT>
=item * C<uid=$username>
=item * C<priv_key_file=path/to/privatekey.p8>
=item * C<priv_key_file_pwd=$private_key_password>
=back
For example:
  db:snowflake://movera@example.snowflakecomputing.com/flipr?Driver=Snowflake;warehouse=sqitch;authenticator=SNOWFLAKE_JWT;uid=movera;priv_key_file=path/to/privatekey.p8;priv_key_file_pwd=s0up3rs3cre7
=back
=head2 Use a Password File
If you must use password authentication with your database server, you may be
able to use a protected password file. This is file with access limited only
to the current user that the server client library can read in. As such, the
format is specified by the database vendor, and not all database servers offer
the feature. Here's how the database engines supported by Sqitch shake out:
=over
=item PostgreSQL, YugabyteDB, CockroachDB
PostgreSQL, YugabyteDB, and CockroachDB will use a
L<F<.pgpass> file|https://www.postgresql.org/docs/current/static/libpq-pgpass.html> in the
user's home directory to or referenced by the C<$PGPASSFILE> environment
variable. This file must limit access only to the current user (C<0600>) and
contains lines specify authentication rules as follows:
  hostname:port:database:username:password
=item MySQL
For MySQL, if the L<MySQL::Config> module is installed, usernames and
passwords can be specified in the
L<F</etc/my.cnf> and F<~/.my.cnf> files|https://dev.mysql.com/doc/refman/5.7/en/password-security-user.html>.
These files must limit access only to the current user (C<0600>). Sqitch will
look for a username and password under the C<[client]> and C<[mysql]>
sections, in that order.
=item Oracle
Oracle supports
L<password file|https://docs.oracle.com/cd/B28359_01/server.111/b28310/dba007.htm#ADMIN10241>
created with the C<ORAPWD> utility to authenticate C<SYSDBA> and C<SYSOPER>
users, but B<Sqitch is unable to take advantage of this functionality.> Neither can
one L<embed a username and password|https://stackoverflow.com/q/7183513/79202>
into a
L<F<tnsnames.ora>|https://docs.oracle.com/cd/B28359_01/network.111/b28317/tnsnames.htm#NETRF007>
file.
=item Vertica
Vertica does not currently support a password file.
=item Firebird
Firebird does not currently support a password file.
=item Exasol
Exasol allows configuring connection profiles for the 'exaplus' client:
  > exaplus -u sys -p exasol -c localhost:8563 -wp flipr_test
  EXAplus 6.0.4 (c) EXASOL AG
  Profile flipr_test is saved.
  > exaplus -profile flipr_test -q -sql "select current_timestamp;"
  CURRENT_TIMESTAMP
  --------------------------
  2017-11-02 13:35:48.360000
These profiles are stored in F<~/.exasol/profiles.xml>, readable only to the user
by default. See the L<documentation|https://www.exasol.com/portal/display/DOC/Database+User+Manual>
for more information on connection profiles, specifically the EXAplus section in
the chapter on "Clients and interfaces".
For ODBC connections from Sqitch, we can use connection settings in F<~/.odbc.ini>:
  [flipr_test]
  DRIVER = Exasol
  EXAHOST = localhost:8563
  EXAUID = sys
  EXAPWD = exasol
  AUTHMETHOD = refreshtoken
When combining the above, Sqitch doesn't need to know any credentials; they are
stored somewhat safely in F<~/.exasol/profiles.xml> and F<~/.odbc.ini>:
  > sqitch status db:exasol:flipr_test
  # On database db:exasol:flipr_test
  # Project:  flipr
  # ...
  #
  Nothing to deploy (up-to-date)
  > sqitch rebase --onto '@HEAD^' -y db:exasol:flipr_test
  Reverting changes to hashtags @v1.0.0-dev2 from db:exasol:flipr_test
    - userflips .. ok
  Deploying changes to db:exasol:flipr_test
    + userflips .. ok
=item Snowflake
For Snowflake, Sqitch will read the
L<F<~/.snowsql/config> file|https://docs.snowflake.com/en/user-guide/snowsql-start.html#snowsql-config-file>
and use the default connections settings; named connections are not supported.
An example:
  [connections]
  accountname = myaccount.us-east-1
  warehousename = compute
  username = frank
  password = fistula postmark bag
  rolename = ACCOUNTADMIN
  dbname = reporting
The variables that Sqitch currently reads are:
=over
=item C<connections.accountname>
=item C<connections.username>
=item C<connections.password>
=item C<connections.rolename>
=item C<connections.region> (Deprecated by Snowflake)
=item C<connections.warehousename>
=item C<connections.dbname>
=back
=back
=head2 Use C<$SQITCH_PASSWORD>
The C<$SQITCH_PASSWORD> environment variable can be used to specify the
password for any supported database engine. However use of this environment
variable is not recommended for security reasons, as some operating systems
allow non-root users to see process environment variables via C<ps>.
The behavior of C<$SQITCH_PASSWORD> is consistent across all supported
engines, as is the complementary C<$SQITCH_USERNAME> environment variable.
Some database engines support their own password environment variables, which
you may wish to use instead. However, their behaviors may not be consistent:
=over
=item PostgreSQL, YugabyteDB, CockroachDB
C<$PGPASSWORD>
=item MySQL
C<$MYSQL_PWD>
=item Vertica
C<$VSQL_PASSWORD>
=item Firebird
C<$ISC_PASSWORD>
=item Snowflake
C<$SNOWSQL_PWD>
=back
=head2 Use Target URIs
Passwords may also be specified in L<target URIs|sqitch-target/Description>.
This is not generally recommended, since such URIs are either specified via
the command-line (and therefore visible in C<ps> and your shell history) or
stored in the L<configuration|sqitch-configuration>, the project instance of
which is generally pushed to your source code repository. But it's provided
here as an absolute last resort (and because web URLs support it, though it's
heavily frowned upon there, too).
Such URIs can either be specified on the command-line:
  sqitch deploy db:pg://fred:s3cr3t@db.example.com/widgets
Or stored as named targets in the project configuration file:
  sqitch target add wigets db:pg://fred:s3cr3t@db.example.com/widgets
After which the target is available by its name:
  sqitch deploy widgets
See L<sqitch-targets> and C<sqitch-configuration> for details  on target
configuration.
=head1 See Also
=over
=item * L<sqitch-environment>
=item * L<sqitch-configuration>
=item * L<sqitch-target>
=back
=head1 Sqitch
Part of the L<sqitch> suite.