{"id":35542,"date":"2024-10-31T08:27:08","date_gmt":"2024-10-31T07:27:08","guid":{"rendered":"https:\/\/www.dbi-services.com\/blog\/?p=35542"},"modified":"2024-10-31T08:27:11","modified_gmt":"2024-10-31T07:27:11","slug":"postgresql-delaying-authentication-to-debug-a-process","status":"publish","type":"post","link":"https:\/\/www.dbi-services.com\/blog\/postgresql-delaying-authentication-to-debug-a-process\/","title":{"rendered":"PostgreSQL: Delaying authentication to debug a process"},"content":{"rendered":"\n<p>While investigating a customer issue (details <a href=\"https:\/\/www.postgresql.org\/message-id\/flat\/GV0P278MB0419EB5885DF99C5354804A9D24B2%40GV0P278MB0419.CHEP278.PROD.OUTLOOK.COM\">here<\/a>) one of the replies suggested to use <a href=\"https:\/\/www.postgresql.org\/docs\/17\/runtime-config-developer.html#GUC-PRE-AUTH-DELAY\" target=\"_blank\" rel=\"noreferrer noopener\">pre_auth_delay<\/a> to add a delay before a session is authenticated. Even if this was not useful for the actual issue, this can be very useful for other scenarios, and this is the reason for this short blog post.<\/p>\n\n\n\n<p>Let&#8217;s assume you know that some of your sessions are doing something unexpected and you want to <a href=\"https:\/\/man7.org\/linux\/man-pages\/man1\/strace.1.html\" target=\"_blank\" rel=\"noreferrer noopener\">strace<\/a> that process from the operating system. The issue is, that those session are very short living and it is hard to know beforehand which session is causing issues. What you can do using <a href=\"https:\/\/www.postgresql.org\/docs\/17\/runtime-config-developer.html#GUC-PRE-AUTH-DELAY\" target=\"_blank\" rel=\"noreferrer noopener\">pre_auth_delay<\/a> is to add a delay before the session is authenticated so you&#8217;re able to identify the process and then attach strace to it. Another use case would be to troubleshoot authentication itself.<\/p>\n\n\n\n<p>The parameter can be changed online (context=sighup), so let&#8217;s change it to 20 seconds:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; highlight: [1,7,9,14]; title: ; notranslate\" title=\"\">\npostgres=# \\dconfig+ pre_auth_delay\n                List of configuration parameters\n   Parameter    | Value |  Type   | Context | Access privileges \n----------------+-------+---------+---------+-------------------\n pre_auth_delay | 10s   | integer | sighup  | \n(1 row)\npostgres=# alter system set pre_auth_delay = &#039;10s&#039;;\nALTER SYSTEM\npostgres=# select pg_reload_conf();\n pg_reload_conf \n----------------\n t\n(1 row)\npostgres=# \\q\n<\/pre><\/div>\n\n\n<p>In another session identify the current psql sessions (as we&#8217;re going to use psql to connect), which returns nothing in my case:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: bash; highlight: [1]; title: ; notranslate\" title=\"\">\npostgres@debian12-pg:\/home\/postgres\/ &#x5B;pgdev] ps -ef | grep psql | grep -v grep\npostgres@debian12-pg:\/home\/postgres\/ &#x5B;pgdev] \n<\/pre><\/div>\n\n\n<p>Start a new psql session, which will block because of the delay we&#8217;ve set:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: bash; highlight: [1]; title: ; notranslate\" title=\"\">\npostgres@debian12-pg:\/home\/postgres\/ &#x5B;pgdev] psql\n<\/pre><\/div>\n\n\n<p>In the other session identify the connection:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: bash; highlight: [1]; title: ; notranslate\" title=\"\">\npostgres@debian12-pg:\/home\/postgres\/ &#x5B;pgdev] ps -ef | grep psql | grep -v grep\npostgres    9750    8637  0 16:57 pts\/1    00:00:00 psql\n<\/pre><\/div>\n\n\n<p>&#8230; and then attach strace to it:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: bash; highlight: [1]; title: ; notranslate\" title=\"\">\npostgres@debian12-pg:\/home\/postgres\/ &#x5B;pgdev] strace -fp 9750\nstrace: Process 9750 attached\npselect6(1, &#x5B;0], NULL, NULL, NULL, {sigmask=&#x5B;], sigsetsize=8}\n<\/pre><\/div>\n\n\n<p>Done. For completeness, there is also <a href=\"https:\/\/www.postgresql.org\/docs\/17\/runtime-config-developer.html#GUC-POST-AUTH-DELAY\" target=\"_blank\" rel=\"noreferrer noopener\">post_auth_delay<\/a>:<\/p>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: sql; highlight: [1]; title: ; notranslate\" title=\"\">\n\npostgres=# \\dconfig+ post_auth_delay\n                List of configuration parameters\n    Parameter    | Value |  Type   | Context | Access privileges \n-----------------+-------+---------+---------+-------------------\n post_auth_delay | 0     | integer | backend | \n(1 row)\n\n<\/pre><\/div>","protected":false},"excerpt":{"rendered":"<p>While investigating a customer issue (details here) one of the replies suggested to use pre_auth_delay to add a delay before a session is authenticated. Even if this was not useful for the actual issue, this can be very useful for other scenarios, and this is the reason for this short blog post. Let&#8217;s assume you [&hellip;]<\/p>\n","protected":false},"author":29,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[229,198],"tags":[77],"type_dbi":[2749],"class_list":["post-35542","post","type-post","status-publish","format-standard","hentry","category-database-administration-monitoring","category-database-management","tag-postgresql","type-postgresql"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v27.2 (Yoast SEO v27.4) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>PostgreSQL: Delaying authentication to debug a process - dbi Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.dbi-services.com\/blog\/postgresql-delaying-authentication-to-debug-a-process\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"PostgreSQL: Delaying authentication to debug a process\" \/>\n<meta property=\"og:description\" content=\"While investigating a customer issue (details here) one of the replies suggested to use pre_auth_delay to add a delay before a session is authenticated. 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He has more than 15 years of experience in management, engineering and optimization of databases and infrastructures, especially on Oracle and PostgreSQL. Since the beginning of his career, he has specialized in Oracle Technologies and is Oracle Certified Professional 12c and Oracle Certified Expert RAC\\\/GridInfra. Over time, Daniel has become increasingly interested in open source technologies, becoming \u201cTechnology Leader Open Infrastructure\u201d and PostgreSQL expert. \u00a0Based on community or EnterpriseDB tools, he develops and installs complex high available solutions with PostgreSQL. He is also a certified PostgreSQL Plus 9.0 Professional and a Postgres Advanced Server 9.4 Professional. He is a regular speaker at PostgreSQL conferences in Switzerland and Europe. Today Daniel is also supporting our customers on AWS services such as AWS RDS, database migrations into the cloud, EC2 and automated infrastructure management with AWS SSM (System Manager). 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He has more than 15 years of experience in management, engineering and optimization of databases and infrastructures, especially on Oracle and PostgreSQL. Since the beginning of his career, he has specialized in Oracle Technologies and is Oracle Certified Professional 12c and Oracle Certified Expert RAC\/GridInfra. Over time, Daniel has become increasingly interested in open source technologies, becoming \u201cTechnology Leader Open Infrastructure\u201d and PostgreSQL expert. \u00a0Based on community or EnterpriseDB tools, he develops and installs complex high available solutions with PostgreSQL. He is also a certified PostgreSQL Plus 9.0 Professional and a Postgres Advanced Server 9.4 Professional. He is a regular speaker at PostgreSQL conferences in Switzerland and Europe. Today Daniel is also supporting our customers on AWS services such as AWS RDS, database migrations into the cloud, EC2 and automated infrastructure management with AWS SSM (System Manager). He is a certified AWS Solutions Architect Professional. Prior to dbi services, Daniel was Management System Engineer at LC SYSTEMS-Engineering AG in Basel. Before that, he worked as Oracle Developper &amp;\u00a0Project Manager at Delta Energy Solutions AG in Basel (today Powel AG). Daniel holds a diploma in Business Informatics (DHBW, Germany). His branch-related experience mainly covers the pharma industry, the financial sector, energy, lottery and telecommunications.","sameAs":["https:\/\/x.com\/westermanndanie"],"url":"https:\/\/www.dbi-services.com\/blog\/author\/daniel-westermann\/"}]}},"_links":{"self":[{"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/posts\/35542","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/users\/29"}],"replies":[{"embeddable":true,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/comments?post=35542"}],"version-history":[{"count":2,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/posts\/35542\/revisions"}],"predecessor-version":[{"id":35544,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/posts\/35542\/revisions\/35544"}],"wp:attachment":[{"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/media?parent=35542"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/categories?post=35542"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/tags?post=35542"},{"taxonomy":"type","embeddable":true,"href":"https:\/\/www.dbi-services.com\/blog\/wp-json\/wp\/v2\/type_dbi?post=35542"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}