From Indonesia, you may apply for a visa to Vietnam either through Vietnamese embassy in Jakarta or apply for a visa on arrival.
Visa on arrival - Visa at Embassy of Vietnam In Jakarta, Indonesia

Embassy of Vietnam in Jakarta, Indonesia
Jalan Teuka Umar 25, Jakarta Pusat
City: Jakarta
Phone: (21) 3100357/8/9
Fax: (21) 3100359 or 3149615
Email: embvnam@uninet.net.id
From other travelers experience, people apply for a visa in Jakarta used to face 2-3 days waiting and a cost of $120 for the same visa.
You can also apply online for a visa on arrival which seems the cheapest and easiest way to get a visa to Vietnam from Jakarta, Indonesia. The total cost is from 35 - 50 USD/person.
http://www.vietnamsvisa.com/vietnam-visa-requirement/vietnam-visa-in-indonesia.html
Visa on arrival - Visa at Embassy of Vietnam In Jakarta, Indonesia

Embassy of Vietnam in Jakarta, Indonesia
Jalan Teuka Umar 25, Jakarta Pusat
City: Jakarta
Phone: (21) 3100357/8/9
Fax: (21) 3100359 or 3149615
Email: embvnam@uninet.net.id
From other travelers experience, people apply for a visa in Jakarta used to face 2-3 days waiting and a cost of $120 for the same visa.
You can also apply online for a visa on arrival which seems the cheapest and easiest way to get a visa to Vietnam from Jakarta, Indonesia. The total cost is from 35 - 50 USD/person.
http://www.vietnamsvisa.com/vietnam-visa-requirement/vietnam-visa-in-indonesia.html